1. Field of the Invention
This invention relates to a mechanism for prevention of temperature increase and ozone removal in an image forming apparatus.
2. Description of the Prior Arts
In recent years, development in the image forming apparatus such as a reproduction machine, etc. tends to be directed toward miniaturization and high-speed operation.
In reducing the size of the reproduction apparatus, it is requisite that every constituent unit of the apparatus be smaller and the apparatus as a whole be highly condensed. Problems which occur in such miniaturization and condensation are the temperature rise within the apparatus and the removal of zone to generate along with the use of corona dischargers. In particular, when a hologen lamp is used for image exposure or heat fixing it is effected by speed increase in operation, and the temperature rise is extreme, with the consequence that there arises various problems such as, in the case of a dry-type development reproduction apparatus, solidification of toner in the developer and cleaner, changes in development density, and change in performance of the photosensitive plate, and, in the case of a wet type development reproduction apparatus, evaporation of solvent due to the temperature rise, changes in development density, and so on. Ozone in its high concentration is harmful, restrictions to which have become more and more stringent.
In the case of a plain paper copier (P.P.C.), large numbers of corona dischargers are used for the latent image formation, image transfer, and so on, hence a large quantity of ozone is generated. For simple prevention of the temperature rise within the apparatus, it is sufficient to increase the quantity of discharging air. However, in the case of performing the ozone adsorption using an ozone filter, it is necessary that the contact time between ozone and activated carbon be prolonged, and the discharging quantity of air in proportion to a certain definite amount of the activated carbon be decreased to augment the adsorption efficiency thereof, or the discharging speed be lowered, or the quantity of the activated carbon be increased with respect to the certain definite discharging quantity of air. In a large-sized reproduction apparatus, it has so far been the practice to independently provide a blower to discharge a large quantity of air to prevent the temperature within the apparatus from rising, and another blower to discharge air containing therein highly concentrated ozone through an ozone filter.
On the contrary, in a small-sized reproduction apparatus, it is very difficult to perfectly segregate the ozone-containing-air and the cooling air. It is also difficult to provide the cooling blower and the ozone removing blower independent of each other from the standpoint of the capacity of the apparatus. Furthermore, it is difficult to provide an ozone filter with a sufficiently large area and capacity.
There is so far known the art of providing discharge openings in the shield plate of the corona discharger so as not to impinge ion wind containing ozone to the photosensitive paper (U.S. Pat. No. 3,777,158), and the art of providing a fan to cause the ozone-containing-air to pass through a catalytic substance (U.S. Pat. No. 3,675,096). However, there has not been known the concept of increasing the filtering effect by concentrating the ozone-containing-air and the heat current at one place in the apparatus.